Prior art safety systems regarding industrial robots have involved alarm and restraint systems of a fixed or static nature over substantially the entire area of the robot's capability of operational movement regardless of the specific area or precise pattern of movements to be made during the operational assignment of the robot. Examples of fixed nature alarm systems are pressure sensitive floor and light beam arrays established around the perimeter of the total capable traval area of the robot, while examples of static restraint systems include a chain or guard rail structure surrounding such overall area of operational capability of the robot.
These prior art safety systems are an inefficient use of floor space or area when the robot is to be operated over only a portion of the area of its capability. Due to this lack of specific correlation between the movement of the robot and the area sensed by the safety system, a false alarm will result should an individual or piece of equipment enter into the controlled area or to a location that would not interfere in any manner with the operational mode of the robot. Thus, the prior art safety systems provide an inefficient means of protection when viewed in terms of operational productivity.
Additionlly, these prior art safety systems are poorly adapted for handling a situation where the robot exhibits aberrant motion, which oftentimes, occurs when the robot is unattended. Aberrant motion usually results when the robot is put on hold, for example, to permit the operator to leave the immediate area, and despite the hold condition, the robot exhibits unprogammed motion. With the prior art safety systems, this aberrant motion will remain undetected unless the robot blocks a light beam or the like of the safety system.